Protective Effects of Thymoquinone against Methotrexate-Induced Germ Cell Apoptosis in Male Mice

Background: Toxic effects of anti-cancer and other drugs on the normal tissues could be reduced by the herbal plants and their fractions. This study investigated the protective effect of thymoquinone (TQ) as a fraction of Nigella sativa on methotrexate (MTX)- induced germ cell apoptosis in male mice. Materials and Methods: In this experimental study, thirty male Balb/c mice were divided randomly into 5 groups (n=6). A single dose of MTX (20 mg/kg) and different concentrations of TQ were administrated for 4 consecutive days. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was performed on paraffin embedded tissue sections to analysis the occurrence of apoptosis in the testis. Reverse transcription polymerase chain reaction (RT-PCR) of apoptosis-related genes was performed with RNA extracted from testes of the mice. Statistical analysis was done using one-way ANOVA. Results: In the MTX group, there was a significant increase in morphologic sign of germ cell degeneration of tubules (48 ± 0.6%), apoptotic index (AI; 2.3 ± 0.6%), as well as mRNA expression of p53 (P=0.008), caspase 8 (P=0.002), caspase 3 (P=0.005), caspase 9 (P=0.000), bax (P=0.004) and the ratio of bax/bcl-2 (P=0.000), whereas there was an decrease in the expression of bcl-2 (P=0.003), as compared to control group. In MTX+TQ groups, the data showed that different concentrations of TQ could improve the harmful effects caused by the MTX. The best protective effects were achieved in MTX+TQ (10 mg/kg). Conclusion: TQ protects testicular germ cell against MTX-induced apoptosis by affecting related genes regulation.